Visualization and classification of epitaxial alignment at hetero-phase boundaries

•We introduce the concept of a Map of Interfacial Periodicity (MIP).•We use this MIP to visualize periodicity within the interface plane.•We introduce a classification system for epitaxial texture components.•Periodic interfaces resulting from plane alignment are the most stable.•NiSi/Ni(001) and α-FeSi2/Si(001) are used to illustrate these concepts.

We use the concept of a Map of Interfacial Periodicity to visualize and classify the periodicity at hetero-phase boundaries. Periodicity in the plane of the interface is a necessary condition to achieve an optimized bonding arrangement across the interface. A periodic boundary plane may be achieved by plane matching, i.e., a 2D match of crystal planes within the plane of the interface, or plane alignment, i.e., matching of lattice planes that are aligned across the interface. The latter mechanism results in axiotaxy and aligned epitaxy and improves robustness for the ‘matching’ nature of the interface with respect to perturbations in grain orientation or interfacial roughness. Examples are presented for different types of epitaxial interfaces between tetragonal α-FeSi2 or orthorhombic NiSi and Si(001), two systems that are known to exhibit both axiotaxial and epitaxial texture components.